Adds padding and perf improvements to wvSplitK_fp8 (#33527)

Signed-off-by: Hashem Hashemi <hashem.hashemi@amd.com>

vllm/model_executor/layers/quantization/kernels/scaled_mm/rocm.py

@@ -25,10 +25,10 @@ def rocm_per_tensor_float_w8a8_scaled_mm_impl(
     bias: torch.Tensor,
 ) -> torch.Tensor:
     if (
-        A.shape[0] == 1
-        and B.shape[1] % 16 == 0
+        A.shape[0] <= 4
+        and B.shape[0] % 16 == 0  # M TODO: needed?
+        and B.shape[1] % 16 == 0  # K
         and ((bias is None) or (bias.dtype == out_dtype))
-        and A.is_contiguous()
     ):
         output = ops.wvSplitKQ(
             B.t(),